Three function thermal-electrical switch

ABSTRACT

A switch that is responsive to both the temperature within an enclosure and the ambient temperature near the exterior of the enclosure. A wax-mixture-filled container at one end of the switch housing monitors the internal temperature of the enclosure and moves a contact assembly within the housing along a pair of terminals in response to the monitored temperature. A bimetal member in the contact assembly effects an electrical connection between the terminals in response to the ambient temperature as sensed within the switch. An insulating member precludes the electrical connection when the wax mixture is above a certain temperature. When the wax mixture is at an even higher temperature the contact assembly completes another current path between one of the terminals and a third terminal.

United States Patent [72] Inventors Alan F. Stocker North Tonawanda;Lynn S. Brock, Williamsville; Raymond E. Gral, Youngstown, all of N.Y.[21] Appl. No. 91,681 [22] Filed Nov. 23, 1970 [45] Patented Nov. 30,1971 [73] Assignee General Motors Corporation Detroit, Mich.

154] THREE FUNCTION THERMAL-ELECTRICAL SWITCH 7 Claims, 7 Drawing Figs.v

152] 0.8. CI 337/299, 73/3683, 337/124 [51] lnt.Cl ..ll0lb 37/52 [50]Field 01 Search 73/3683, 363.5; 337/299, 124, 382, 389, 398, 399,101;234/34; 200/153 M [56] References Cited UNITED STATES PATENTS 2.265.58612/1941 Vernet 73/368.3

52A fi an d? Primary Examiner-.1. V. Truhe Assistant Examiner-L. A.Schutzman Artorneys-.l. L. Carpenter and Paul Fitzpatrick ABSTRACT: Aswitch that is responsive to both the temperature within an enclosureand the ambient temperature near the exterior of the enclosure. Awax-mixture-filled container at one end of the switch housing monitorsthe internal temperature of the enclosure and moves a contact assemblywithin the housing along a pair of terminals in response to themonitored temperature. A bimetal member in the contact assembly effectsan electrical connection between the terminals in response to theambient temperature as sensed within the switch. An insulating memberprecludes the electrical connection when the wax mixture is above acertain temperature. When the wax mixture is at an even highertemperature the contact assembly completes another current path betweenone of the terminals and a third terminal.

THREE FUNCTION THERMAL-ELECTRICAL SWITCH This invention relates'tomultiple function switches and, more particularly, to switches that areresponsive both to the temperature within an enclosure and to theambient temperature without the enclosure.

In the switch, or control device, field there are a multitude ofdesigns, many of which have been devised to perform a given function tofulfill a certain need. In the present instance it has been observedthat modern automobiles employing internal combustion engines operatebest when their ignition is advanced or retarded in accordance with boththe temperature of the engine, as measured by the engine coolant temperature, and the ambient temperature adjacent the engine, as measuredwithin the engine compartment of a vehicle. In addition, experience hassuggested the need of indicating to a vehicle occupant when thetemperature of the engine is excessive so as to preclude his operatingthe vehicle in a fashion which will damage the engine.

It is, therefore, an object of this invention to provide a switch whichelectrically connects a pair of terminals in response to both thetemperature within an enclosure and also electrically connects a thirdterminal to one of the other terminals in response to the enclosureinternal temperature.

' It is another object of this invention to provide a switch whichemploys a wax mixture to monitor the internal temperature of an enc reand a bimetal element to monitor the amdjacent the enclosure and whichelectri- M urality of terminals in response to the monitored temperares.

It is yet another object of this invention to provide a switch whichmonitors the coolant temperature of an engine with a reservoircontaining a heat expansible substance that undergoes substantialvolumetric increases at certain tempera tures, the switch controlling aplurality of electrical connections in response to expansion of thesubstance.

The foregoing and other objects and advantages of the subject inventionwill become apparent from the accompanying description and drawings, inwhich:

FIGS. 1 through 3 are schematic diagrams illustrating variousoperational conditions of a switch embodying the principles of thesubject invention;

FIG. 4 is a perspective view of the switch in FIGS. 1 through FIG. showsa contact assembly employed in the switch of FIGS. 1 through 4;

FIG. 6 is a plan view of the contact assembly is FIG. and

FIG. 7 is an exploded view of the contact assembly in FIG. 5.

As shown in FIGS. 1 through 3, a switch 10 according to the principlesof the subject invention may be employed to control the energization ofa control network 12 and a lamp 14 by a battery 16 in accordance withthe temperature within an enclosure 18 and the ambient temperatureadjacent the enclosure 18. For example, the enclosure 18, a section ofwhich is shown in FIGS. 1 through 3, may be the portion of a vehicleengine that is filled with engine coolant 20 and is commonly called awater jacket. In addition, the lamp 14 may be a HOT telltale of awell-known type employed to indicate that the coolant 20 is excessivelyhot, and that the control network 12 may be of a type designed tocontrol the ignition timing of the engine l8.

As persons versed in the art will appreciate, the timing of a vehiclesignition greatly affects the operation of the vehicle. Many modernvehicles therefore employ apparatus for utilizing the intake manifoldvacuum of an engine to advance the ignition supplied the engine by adistributor when the engine is operating under certain conditions, theapplication of the manifold vacuum to the distributor being controlledby an electrical solenoid. For purposes of this description, it sufiicesto state that the network 12 controls the engine 18 in this fashion andthat the ignition which is supplied the engine 18 by a suitable ignitionsystem (not shown) may be advanced whenever the lead 22 that connectsthe switch 10 to the net work 12 is deenergized. Conversely, when theswitch 10 electrically connects the lead 22 to the battery 16 the lead22 is energized so as to preclude the network 12 from advancing theignition supplied to the engine 18.

The switch 10 includes a housing 24 having a cover section 26 and anelectrically grounded base section 28, a portion 30 of the base section28 being threaded for insertion into a threaded hole in the engine 18.For convenience in manufacturing the housing 24, it may be desirable tocrimp the base section 28 over the cover section 26, as shown in FIG. 4.A heat transferring reservoir 32 which contains a wax mixture 34 issecured to the base section 28 so as to extend into the coolant 20 formonitoring the coolant 20 temperature. By way of example, the reservoir32 may b made of copper alloy which readily transmits heat so that thewax mixture 34 partakes of the temperature inside the engine 18.

As persons versed in the art will appreciate, many waxes arecharacterized as undergoing substantial volumetric expansion whilemelting. Typical of these waxes are beeswax and paraffin, either ofwhich may be used in the wax mixture 34. Accordingly, each time thecoolant 20 temperature exceeds the melting temperature of a wax in a waxmixture, the wax is melted and the volume of the wax mixture 34 iscorrespondingly increased, the waxes having higher melting temperaturesremaining solidified in the wax mixture as waxes having lower meltingtemperatures are changed from the solid to the liquid state. While theswitch 10 structure may be modified to accommodate several changes inthe wax mixture 34 volume, the illustrated embodiment of the switch 10is designed to accommodate two waxes in the wax mixture 34, one waxhaving a melting temperature of approximately 220 F. and the other waxhaving a melting temperature of approximately 252 F. The wax mixture 34may also include a substance which increases the thermal conductivity ofthe wax mixture 34, to facilitate rapid melting of the waxes as each oftheir respective melting temperatures are reached by the engine coolant20. Copper powder suspended in the wax mixture 34 has been found to beespecially useful for this purpose.

A cover member 36 is provided for sealing the reservoir 32 so as topreclude the wax mixture 34 from escaping from the reservoir 32 into thecentral portion of the housing 24. In the illustrated embodiment, anouter lip 38 of the reservoir 32 is crimped over the cover member 36 soas to tightly enclose the reservoir 32. To allow for expansion of thewax mixture 34 as the waxes are melted, the cover member 36 contains anaperture in which is slidably positioned a plunger 40 that is dr'ivablycoupled to a contact assembly 42. As will subsequently be explained,hydraulic pressure in the wax mixture 34 causes the plunger 40 to behydraulically expelled from the reservoir 32 as each of the waxes in thewax mixture 34 is melted.

The contact assembly 42 includes a contact support member 44 whichsupports first and second spring contacts 46 and 48 and a bimetalelement 50, as shown in greater detail in FIGS. 5 through 7. The contactsupport member 44 is recessed, as shown at 45 to facilitate coupling thecontact support member 44 to the plunger 40. Accordingly, as the plunger40 is expelled from the reservoir 32, as shown in FIGS. 2 and 3, thecontact assembly 42 is moved in its entirety away from the engine 18.

The switch 10 includes first and second terminals 52 and 54 which servethe dual purpose of accommodating external connections to the switch 10and of guiding the contact assembly 42 as it is moved by the plunger 40.As shown in FIG. 1, the contacts 46 and 48 are self-biased into slidableengagement with the terminals 52 and 54, which extend through apertures56 and 58 in the contact support member 44. The lower most ends 60 and62 of the terminals 52 and 54 are bent at right angles so as to supportthe contact support member 44. A compressive spring 64 is provided forbiasing the contact support member 44 against the plunger 40 so as topush the plunger 40 into the wax mixture 34 until either the contactsupport member 44 is supported by the ends 60 and 62 of the first andsecond terminals 52 and 54 or the hydraulic pressure in the reservoir 32offsets the force applied to the plunger 40 by the spring 64.

As the'plunger 40 is expelled from the reservoir 32 by the lower meltingtemperature wax in the wax mixture 34 melting the first contact 46,which is rounded at its free end 65, is physically separated from thefirst terminal 53 by an insulating member 66 having a sloped end 67.When the higher melting temperature wax in the wax mixture 34 is melted,the extension of the plunger 40 the reservoir 32 is at a maximum and anelectrical connection is effected from the second contact 48 to the lamp14 through a third electrical terminal 68, which includes an adjustmentscrew 70, as will now be explained in conjunction with FIGS. 2 and 3.

When it is desired to operate the engine 18 in weather above 67 F. thebimetal member 50, which in the illustrated embodiment is in the form ofa snap disc having a snapping temperature of approximately 67 F., is inthe position illustrated in FIG. 5. When the snap disc 50 is in thisposition, the first contact 46 is biased into engagement with the secondcontact 48 by the snap disc 50 due to the warm ambient temperature.

Since the warm weather conditions would also place the engine l8 and thecoolant at the same temperature as the snap disc 50, which temperatureis assumed to be greater than the 67 F. but less than 220 F., both ofthe waxes in the wax mixture 34 are in a solid state. The plunger 40extension from the reservoir 32 is then held at a minimum by the spring64. Accordingly, under these conditions the lead 22 is energized by thebattery 16 through the first and second terminals 52 and 54 and thecontacts 46 and 48, as previously mentioned. When the lead 22 isenergized it may be assumed that the control network 12 precludesadvancing the engine 18 ignition by means of the intake manifold vacuum.

However, when the temperature of the coolant 20 exceeds 220 F., thelower melting of the waxes in the wax mixture 34 is melted, causing theplunger 40 to be hydraulically expelled from the reservoir 32 to thepartially expelled position illustrated in FIG. 2. Since the firstcontact 46 is electrically insulated from the first terminal 52 by theinsulating member 66 when the plunger 40 is in the partially expelledposition of FIG. 2, the lead 22 is deenergized and the control network12 is allowed to advance the ignition timing of the engine 18. Aspersons versed in the art will appreciate, advancing the ignition of theengine 18 when the coolant 20 is hot allows the engine 18 to operate ata cooler temperature.

Should the temperature of the coolant 20 be increased past the meltingtemperature of the second wax, the plunger 40 is then hydraulicallyexpelled from the reservoir 32 to its fully extended positionillustrated in FIG. 3 so as to engage the screw 70 with the secondcontact 48. This completes a current path from the battery 16 throughthe second terminal 54, the second contact 48, the third terminal 68,and the lamp 14 so as to energize the lamp 114 and advise the vehicleoperator of the overheated condition of the engine 18.

When the engine is started under cold ambient conditions that are below68 F., both of the waxes in the wax mixture 34 are in a solid state andthe snap disc 50 is in the position illustrated in FIG. 1. Since thecontacts 46 and 88 are not closed by the snap disc 50 under theseconditions, the lead 22 is initially deenergized when the engine 18 isstarted. Accordingly, the control network 12 is able to advance theignition timing of the engine 18 to assure that the engine I8 is able toidle smoothly and provide the vehicle occupants with the level ofperformance which they desire. Under these cold conditions, the engine18 is normally provided with a richer fuel mixture; i.e., one whichcontains an increased percentage of fuel, so that the advanced ignitiontime of the engine 18 provides the engine 18 with an increasedopportunity to assure complete combustion of the fuel which it receives.Once the ambient temperature adjacent the engine 18 has been increasedabove 67 F. the snap disc 50 is changed to the position illustrated inFlG. 5 so as to close the contacts 46 and 48 and energize the lead 22.When the lead 22 is energized, the control network 12 is precluded fromfurther advancing of the engine 18 timmg.

When the engine 18 has warmed sufficiently so that the coolant 20 isabove 220' F., the wax in the wax mixture 34 having the lower meltingtemperature is melted so as to partially expel the plunger 40 from thereservoir 32, causing the insulating member as to separate the firstcontact 46 from the first terminal 52. When the first contact 46 isseparated from the first terminal 52, the lead 22 is no longer energizedthrough the switch 10 and the control network 12 is again permitted toadvance the ignition timing of the engine 18, causing it to run cooler.Thereafter, the operation of the switch It) continues as previouslyexplained.

While the switch herein described has been discussed in conjunction withapparatus for controlling the timing of a vehicle enm'ne, persons versedin the art will appreciate that the switch may be used in a wide varietyof other systems without departing from the spirit of this invention.

What is claimed is:

l. A multiple function switch that is responsive both to the temperaturewithin an enclosure and the ambient temperature without the enclosurecomprising, in combination, a housing; a heat transferring reservoiradapted for insertion into the enclosure and secured to the housing;fist means mechanically responsive to temperature positioned within thereservoir for monitoring the interior temperature of the enclosurethrough the reservoir, said means assuming a first condition when theenclosure interior temperature is below a certain temperature and asecond condition when the enclosure interior temperature is above thecertain temperature; at least first and second electrical terminalspositioned within the housing and extending outside the housing forconnection of external leads thereto; contact means for completing anelectrical connection between the first and second terminals inaccordance with the enclosure interior temperature and the ambienttemperature, said contact means including a contact support member thatis driveably coupled to said first means for movement therewith, atleast first and second contacts secured to the contact support member,each contact being biased into sliding engagement with one of theterminals, and second means mechanically responsive to temperaturesecured to the contact support member for monitoring the ambienttemperature within the housing and for effecting an electricalconnection between the contacts in response to the ambient temperature,thereby electrically connecting the terminals in accordance with theambient temperature; and means for electrically insulating the fistcontact from the terminal it engages when said first means is in one ofsaid conditions and permit the first contact to engage the terminal whensaid first means is in the other condition so as to effect an electricalconnection between terminals in response to changes in the enclosureinten'or temperature.

2. A multiple function switch that is responsive to both the temperaturewithin an enclosure and the ambient temperature outside the enclosurecomprising, in combination, a housing; a heat transferring reservoirsecured to the housing and adapted for insertion into the enclosure, thereservoir being enclosed except for an aperture which communicates withthe interior of the housing; a wax mixture disposed in the reservoir soas to be responsive to the temperature within the enclosure, the waxesin the wax mixture each being characterized by considerable volumetricexpansion while melting; a plunger slidably positioned in the apertureso as to extend into the wax mixture whereby expansion of the waxmixture partially expels from the plunger from the reservoir into thehousing; a plurality of electrically isolated conductive terminalspositioned os as to extend into the housing from outside the housing;and means for electrically connecting the terminals within the housingin response to the temperature within the enclosure and the ambienttemperature as sensed within the housing, said means including a contactsupport member driveably coupled to the plunger for movement therewithin response to melting of the wax by the enclosure internal temperature,the

plunger moving the contact support member from a first position to asecond position when the wax is changed between liquid and solid phases,at least first and second electrically isolated contacts mounted on thecontact support member, each of the contacts being biased to slidablyengage one of the terminals, one of the terminals being positioned forengagement by one of the contacts when the contact support member is inone of said positions, means for preventing said one contact fromengaging said one terminal when the contact support member is in theother of said positions, thereby electrically connecting at least two ofthe terminals in response to the temperature inside the enclosure, andmeans mechanically responsive to temperature mounted on the contactsupport member for sensing the ambient temperature within the housingand for electrically connecting the contacts in response to the ambienttemperature, thereby electrically connecting at least two of theterminals in response to the ambient temperature.

3. A switch that is responsive to both ambient temperature and thetemperature within an enclosure comprising, in combination, a housing, aportion of the housing being adapted for insertion into the enclosure; aheat transmitting reservoir secured to said housing portion so as toextend externally of the housing efiective to partake of the enclosureinterior temperature when said housing portion is inserted into theenclosure; means mechanically responsive to temperature positioned inthe reservoir so as to partake of the enclosure interior temperaturethrough the reservoir; a plunger driveably coupled to said means andpositioned so as to protrude into both the reservoir and the interior ofthe housing, said means being characterized as having a first conditionin which the extension of the plunger from the reservoir is at a minimumwhen said means is below a certain temperature, a second condition inwhich the plunger is partially expelled from the reservoir by said meanswhen said means is above the certain temperature, and a third conditionin which the expulsion of the plunger from the reservoir by said meansis at a maximum when said means is above an elevated temperature that ishigher than the certain temperature; a contact assembly including acontact support member driveably coupled to the plunger for movementtherewith, first and second electrically isolated contacts supported bythe contact support member, and second means mechanically responsive totemperature supported by the contact support member for effecting anelectrical connection between the contacts in response to the ambienttemperature as sensed by said second mechanically responsive meanswithin the interior of the housing; at least first, second and thirdelectrical terminals extending within the housing from without thehousing, the first and second terminals each being positioned forengagement by one of the contacts as the plunger moves the contactassembly, thereby enabling the second mechanically responsive means toeffect an electrical connection between the first and second terminalsin response to ambient temperature; and the third terminal beingpositioned so that the second contact is moved into engagement therewithwhen the expulsion of the plunger from the container is at said maximumand the enclosure interior temperature is above the elevatedtemperature; insulating means positioned within the housing forseparating the first contact from the terminal it engages when theextension of the plunger from the container has reached said partiallyexpelled state indicative of the enclosure interior temperature beingabove the certain temperature, thereby preventing the first terminalfrom being in electrical contact with the second terminal when theenclosure interior temperature is above the certain temperature; andmeans for biasing the plunger into the reservoir when the plunger is notexpelled from the reservoir by the first mentioned mechanicallyresponsive means.

4. A switch that is responsive to both ambient temperature and thetemperature within an enclosure comprising, in combination, a housing, aportion of the housing being adapted for insertion into the enclosure; aheat transmitting reservoir secured to said housing portion so as toextend externally of the housing effective to partake of the enclosureinterior temperature when said housing portion is inserted into theenclosure a mixture of at least two heat expansible substances havingdifferent melting temperatures positioned in the reservoir so as topartake of the enclosure interior temperature through the reservoir;each substance in the mixture being characterized as undergoingsubstantial volumetric expansion while melting; means for enclosing thecontainer for preventing the mixture from passing between the reservoirand the interior of the housing; a plunger positioned in said meanseffective to extend both into the housing and into the reservoir so asto be responsive to the volume of the mixture, the mixture hydraulicallyexpelling the plunger from the reservoir as each substance is melted sothat the extension of the plunger from the reservoir is an indication ofthe enclosure interior temperature; a contact assembly including acontact support member driveably coupled to the plunger for movementtherewith, first and second electrically isolated contacts supported bythe contact support member, and means mechanically responsive to theambient temperature supported by the contact support member by effectingan electrical connection between the contacts in response to the ambienttemperature; at least first, second and third electrical terminalssecured to the housing so as to extend therethrough, the first andsecond terminals being positioned such that the first contact is insliding engagement with the first terminal and the second contact is insliding engagement with the second terminal so that the mechanicallyresponsive means effects an electrical connection between the first andsecond terminals in response to the ambient temperature, the contactsbeing moved relative to the terminals when the plunger moves the contactassembly, the third terminal being positioned so that the second contactis moved into engagement therewith when both of the substances aremelted by the enclosure interior temperature whereby the second contactelectrically connects the second and third terminals when the enclosureinterior temperature is sufficiently high to melt both of thesubstances; insulating means positioned within the housing so as toseparate the first contact from the first terminal when the enclosureinterior temperature has melted the lower melting temperaturesubstances, thereby preventing the first terminal from being inelectrical contact with the second tenninal when said substance ismelted; and means for biasing the plunger into the reservoir as thesubstances are solidified.

5. A switch that is responsive to both ambient temperature and thetemperatures within an enclosure comprising, in combination, a housing,a portion of the housing being adapted for insertion into the enclosurea heat transmitting reservoir secured to said housing portion so as toextend externally of the housing effective to partake of the enclosureinterior temperature when said housing portion is inserted into theenclosure a mixture of two waxes having different melting temperaturepositioned in the reservoir so as to partake of the enclosure interiortemperature through the reservoir, each wax in the wax mixture beingcharacterized as undergoing substantial volumetric expansion whilemelting, a cover member positioned to prevent the waxes from passingbetween the reservoir and the interior of the housing, the cover memberhaving an aperture which communicates between the interior of thehousing and the interior of the container; a plunger slidably positionedin the aperture so as to extend into the reservoir and be responsive tothe volume of the wax mixture, volumetric expansion of the wax mixturehydraulically expelling the plunger from the reservoir as each wax ismelted such that the extension of the plunger from the reservoir isindicative of the interior temperature of the enclosure; a contactassembly including a contact support member driveably coupled to theplunger for movement therewith, first and second electrically isolatedcontacts supported by the contact support member, and means mechanicallyresponsive to temperature supported by the contact support member foreffecting an electrical connection between the contacts in response tothe ambient temperature; at least first, second and third electricalterminals secured to the housing so as to extend therethrough, the firstand second terminals being positioned so that the first contact is insliding engagement with the first terminal and the second contact is insliding engagement with the second terminal, the third terminal beingpositioned so that the second contact is moved into engagement therewithwhen both of the waxes are melted by the enclosure interior temperaturewhereby the second contact electrically connects the second and thirdterminals when the enclosure interior temperature is sufficiently highto melt both of the waxes; insulating means positioned within thehousing so as to separate the first contact from the first terminal whenthe enclosure interior temperature has melted the lower meltingtemperature wax, thereby preventing the first tenninal from being inelectrical contact with the second terminal when said wax is melted; andmeans for biasing the plunger into the reservoir as the waxes aresolidified by a cooling of the enclosure interior temperature.

6. A switch that is responsive to both ambient temperature and thetemperature within an enclosure comprising, in combination, a housing, aportion of the housing being adapted for insertion into the enclosure; aheat transmitting reservoir secured to said housing portion so as toextend externally of the housing effective to partake of the enclosureinterior temperature when said housing portion is inserted into theenclosure; a wax mixture including at least two waxes having differentmelting temperatures and a substance characterized as having substantialthermal conductivity positioned in the reservoir so as to partake of theenclosure interior temperature through the reservoir, each wax in thewax mixture being characterized as undergoing substantial volumetricexpansion while melting; a cover member positioned to prevent the waxesfrom passing between the reservoir and the interior of the housing, thecover member having an aperture which communicates between the interiorof the housing and the interior of the reservoir; an elongated plungerslidably positioned in the aperture so as to extend into the reservoirand be responsive to the volume of the wax mixture, volumetric expansionof the wax mixture hydraulically expelling the plunger from thereservoir as each wax is melted such that the extension of the plungerfrom the reservoir is indicative of the interior temperature of theenclosure; a contact assembly including a contact support member whichcontains at least two apertures and which is driveably coupled to theplunger for movement therewith, first and second electrically isolatedcontacts supported by the contact support member, and means mechanicallyresponsive to temperature supported by the contact support member foreffecting an electrical connection between the contacts in response tothe ambient temperature; first and second elongated electrical terminalssecured to the housing so as to extend therethrough and be orientedsubstantially parallel with'the plunger, the first and second terminalseach being positioned so as to extend through an aperture in the contactsupport member and to be in slidable engagement with one of the contactsand the contact support member such that the first contact is in slidingengagement with the first terminal and the second contact is in slidingengagement with the second terminal, movement of the plunger therebymoving the contacts and the contact support member relative to theterminals, the terminals thereby guiding the contact support member;insulating means positioned within the housing so as to separate thefirst contact from the first terminal when the enclosure interiortemperature has melted the lower melting temperature wax so as topartially expel the plunger from the reservoir, thereby preventing thefirst terminal from being in electrical contact with the second terminalwhensaid wax is melted; a third electrical tenninal secured to thehousing and extending therethrough so as to be engaged by the secondcontact when both of the waxes are melted by the enclosure interiortemperature and the expulsion of the plunger from the reservoir is at amaximum, the second contact thereby electrically connecting the secondand third terminals when the enclosure interior temperatureis'sufficiently high to melt both of the waxes; and means for biasingthe plunger into the reservoir as the waxes are solidified.

7. A switch that is responsive to both ambient temperature and thetemperature within an enclosure comprising, in combination, a housing, aportion of the housing being adapted for insertion into the enclosure; aheat transmitting reservoir secured to the housing so as to extendexternally of the housing effective to partake of the enclosure interiortemperature when said housing portion is inserted into the enclosure; amixture of two waxes having different melting temperatures positioned inthe reservoir so as to partake of the enclosure interior temperaturethrough the reservoir, each wax in the wax mixture being characterizedas undergoing substantial volumetric expansion while melting; a covermember positioned to prevent the waxes from passing between thereservoir and the interior of the housing, the cover member having anaperture which communicates between the interior of the housing and theinterior of the reservoir; a plunger slidably positioned in the apertureso as to extend into the reservoir and be responsive to the volume ofthe wax mixture, volumetric expansion of the wax mixture hydraulicallyexpelling the plunger from the reservoir as each wax is melted such thatthe extension of the plunger from the reservoir is dependent upon theinterior temperature of the enclosure; a contact assembly including acontact support member driveably coupled to the plunger for movementtherewith, first and second electrically isolated contacts supported bythe contact support member, 'and means mechanically responsive totemperature supported by the contact support member for effecting anelectrical connection between the contacts in response to the ambienttemperature; at least first, second and third electrical terminalssecured to the housing so as to extend therethrough, the first andsecond terminals being positioned so that the first contact is insliding engagement with the first terminal and the second contact is insliding engagement with the second terminal as the plunger moves thecontact assembly, the third terminal being positioned so that the secondcontact is moved into engagement therewith when both of the waxes aremelted by the enclosure interior temperature whereby the second contactelectrically connects the second and third terminals when the enclosureinterior temperature is sufiiciently high to melt both of the waxes;insulating means positioned within the housing so as to separate thefirst contact from the first terminal when the enclosure interiortemperature has melted the lower melting temperature wax, therebypreventing the first terminal from being in electrical contact with thesecond terminal when said wax is melted; and means for biasing theplunger into the reservoir as the waxes are solidified.

g ga UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent: No.3,624,578 Dated November 30, 1971 Alan F. Stocker, ln e w ls) Lynn 5.Brock and Raymond E. Graf It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Column 1, line 44, after "Fig. insert 5 Column 2, line 13, "b" shouldread be line 22, "a" (second occurrence) should read the Column 3, line6, "53" should read 52 line 9, after "40 insert from line 28, "then"should read thus line 57, "68 should read 67 Column 4, line 17, after"be" insert modified considerably from the embodiment herein describedand may be ----7 line 25, "fist" should read first line 48, "fist"should read first line 67, delete "from"; line 68, os" should read soColumn 6, line 22, "by" should read for Signed and sealed this 26th dayof September 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOT'ISCHALK Attesting Officer Commissionerof Patents

1. A multiple function switch that is responsive both to the temperaturewithin an enclosure and the ambient temperature without the enclosurecomprising, in combination, a housing; a heat transferring reservoiradapted for insertion into the enclosure and secured to the housing;fist means mechanically responsive to temperature positioned within thereservoir for monitoring the interior temperature of the enclosurethrough the reservoir, said means assuming a first condition when theenclosure interior temperature is below a certain temperature and asecond condition when the enclosure interior temperature is above thecertain temperature; at least first and second electrical terminalspositioned wiThin the housing and extending outside the housing forconnection of external leads thereto; contact means for completing anelectrical connection between the first and second terminals inaccordance with the enclosure interior temperature and the ambienttemperature, said contact means including a contact support member thatis driveably coupled to said first means for movement therewith, atleast first and second contacts secured to the contact support member,each contact being biased into sliding engagement with one of theterminals, and second means mechanically responsive to temperaturesecured to the contact support member for monitoring the ambienttemperature within the housing and for effecting an electricalconnection between the contacts in response to the ambient temperature,thereby electrically connecting the terminals in accordance with theambient temperature; and means for electrically insulating the fistcontact from the terminal it engages when said first means is in one ofsaid conditions and permit the first contact to engage the terminal whensaid first means is in the other condition so as to effect an electricalconnection between terminals in response to changes in the enclosureinterior temperature.
 2. A multiple function switch that is responsiveto both the temperature within an enclosure and the ambient temperatureoutside the enclosure comprising, in combination, a housing; a heattransferring reservoir secured to the housing and adapted for insertioninto the enclosure, the reservoir being enclosed except for an aperturewhich communicates with the interior of the housing; a wax mixturedisposed in the reservoir so as to be responsive to the temperaturewithin the enclosure, the waxes in the wax mixture each beingcharacterized by considerable volumetric expansion while melting; aplunger slidably positioned in the aperture so as to extend into the waxmixture whereby expansion of the wax mixture partially expels from theplunger from the reservoir into the housing; a plurality of electricallyisolated conductive terminals positioned os as to extend into thehousing from outside the housing; and means for electrically connectingthe terminals within the housing in response to the temperature withinthe enclosure and the ambient temperature as sensed within the housing,said means including a contact support member driveably coupled to theplunger for movement therewith in response to melting of the wax by theenclosure internal temperature, the plunger moving the contact supportmember from a first position to a second position when the wax ischanged between liquid and solid phases, at least first and secondelectrically isolated contacts mounted on the contact support member,each of the contacts being biased to slidably engage one of theterminals, one of the terminals being positioned for engagement by oneof the contacts when the contact support member is in one of saidpositions, means for preventing said one contact from engaging said oneterminal when the contact support member is in the other of saidpositions, thereby electrically connecting at least two of the terminalsin response to the temperature inside the enclosure, and meansmechanically responsive to temperature mounted on the contact supportmember for sensing the ambient temperature within the housing and forelectrically connecting the contacts in response to the ambienttemperature, thereby electrically connecting at least two of theterminals in response to the ambient temperature.
 3. A switch that isresponsive to both ambient temperature and the temperature within anenclosure comprising, in combination, a housing, a portion of thehousing being adapted for insertion into the enclosure; a heattransmitting reservoir secured to said housing portion so as to extendexternally of the housing effective to partake of the enclosure interiortemperature when said housing portion is inserted into the enclosure;means mechanically responsive to temperature positioned in the resErvoirso as to partake of the enclosure interior temperature through thereservoir; a plunger driveably coupled to said means and positioned soas to protrude into both the reservoir and the interior of the housing,said means being characterized as having a first condition in which theextension of the plunger from the reservoir is at a minimum when saidmeans is below a certain temperature, a second condition in which theplunger is partially expelled from the reservoir by said means when saidmeans is above the certain temperature, and a third condition in whichthe expulsion of the plunger from the reservoir by said means is at amaximum when said means is above an elevated temperature that is higherthan the certain temperature; a contact assembly including a contactsupport member driveably coupled to the plunger for movement therewith,first and second electrically isolated contacts supported by the contactsupport member, and second means mechanically responsive to temperaturesupported by the contact support member for effecting an electricalconnection between the contacts in response to the ambient temperatureas sensed by said second mechanically responsive means within theinterior of the housing; at least first, second and third electricalterminals extending within the housing from without the housing, thefirst and second terminals each being positioned for engagement by oneof the contacts as the plunger moves the contact assembly, therebyenabling the second mechanically responsive means to effect anelectrical connection between the first and second terminals in responseto ambient temperature; and the third terminal being positioned so thatthe second contact is moved into engagement therewith when the expulsionof the plunger from the container is at said maximum and the enclosureinterior temperature is above the elevated temperature; insulating meanspositioned within the housing for separating the first contact from theterminal it engages when the extension of the plunger from the containerhas reached said partially expelled state indicative of the enclosureinterior temperature being above the certain temperature, therebypreventing the first terminal from being in electrical contact with thesecond terminal when the enclosure interior temperature is above thecertain temperature; and means for biasing the plunger into thereservoir when the plunger is not expelled from the reservoir by thefirst mentioned mechanically responsive means.
 4. A switch that isresponsive to both ambient temperature and the temperature within anenclosure comprising, in combination, a housing, a portion of thehousing being adapted for insertion into the enclosure; a heattransmitting reservoir secured to said housing portion so as to extendexternally of the housing effective to partake of the enclosure interiortemperature when said housing portion is inserted into the enclosure amixture of at least two heat expansible substances having differentmelting temperatures positioned in the reservoir so as to partake of theenclosure interior temperature through the reservoir; each substance inthe mixture being characterized as undergoing substantial volumetricexpansion while melting; means for enclosing the container forpreventing the mixture from passing between the reservoir and theinterior of the housing; a plunger positioned in said means effective toextend both into the housing and into the reservoir so as to beresponsive to the volume of the mixture, the mixture hydraulicallyexpelling the plunger from the reservoir as each substance is melted sothat the extension of the plunger from the reservoir is an indication ofthe enclosure interior temperature; a contact assembly including acontact support member driveably coupled to the plunger for movementtherewith, first and second electrically isolated contacts supported bythe contact support member, and means mechanically responsive to theambient temperature supported by the contact support member by effectingaN electrical connection between the contacts in response to the ambienttemperature; at least first, second and third electrical terminalssecured to the housing so as to extend therethrough, the first andsecond terminals being positioned such that the first contact is insliding engagement with the first terminal and the second contact is insliding engagement with the second terminal so that the mechanicallyresponsive means effects an electrical connection between the first andsecond terminals in response to the ambient temperature, the contactsbeing moved relative to the terminals when the plunger moves the contactassembly, the third terminal being positioned so that the second contactis moved into engagement therewith when both of the substances aremelted by the enclosure interior temperature whereby the second contactelectrically connects the second and third terminals when the enclosureinterior temperature is sufficiently high to melt both of thesubstances; insulating means positioned within the housing so as toseparate the first contact from the first terminal when the enclosureinterior temperature has melted the lower melting temperaturesubstances, thereby preventing the first terminal from being inelectrical contact with the second terminal when said substance ismelted; and means for biasing the plunger into the reservoir as thesubstances are solidified.
 5. A switch that is responsive to bothambient temperature and the temperatures within an enclosure comprising,in combination, a housing, a portion of the housing being adapted forinsertion into the enclosure a heat transmitting reservoir secured tosaid housing portion so as to extend externally of the housing effectiveto partake of the enclosure interior temperature when said housingportion is inserted into the enclosure a mixture of two waxes havingdifferent melting temperature positioned in the reservoir so as topartake of the enclosure interior temperature through the reservoir,each wax in the wax mixture being characterized as undergoingsubstantial volumetric expansion while melting, a cover memberpositioned to prevent the waxes from passing between the reservoir andthe interior of the housing, the cover member having an aperture whichcommunicates between the interior of the housing and the interior of thecontainer; a plunger slidably positioned in the aperture so as to extendinto the reservoir and be responsive to the volume of the wax mixture,volumetric expansion of the wax mixture hydraulically expelling theplunger from the reservoir as each wax is melted such that the extensionof the plunger from the reservoir is indicative of the interiortemperature of the enclosure; a contact assembly including a contactsupport member driveably coupled to the plunger for movement therewith,first and second electrically isolated contacts supported by the contactsupport member, and means mechanically responsive to temperaturesupported by the contact support member for effecting an electricalconnection between the contacts in response to the ambient temperature;at least first, second and third electrical terminals secured to thehousing so as to extend therethrough, the first and second terminalsbeing positioned so that the first contact is in sliding engagement withthe first terminal and the second contact is in sliding engagement withthe second terminal, the third terminal being positioned so that thesecond contact is moved into engagement therewith when both of the waxesare melted by the enclosure interior temperature whereby the secondcontact electrically connects the second and third terminals when theenclosure interior temperature is sufficiently high to melt both of thewaxes; insulating means positioned within the housing so as to separatethe first contact from the first terminal when the enclosure interiortemperature has melted the lower melting temperature wax, therebypreventing the first terminal from being in electrical contact with thesecond terminal when said wax Is melted; and means for biasing theplunger into the reservoir as the waxes are solidified by a cooling ofthe enclosure interior temperature.
 6. A switch that is responsive toboth ambient temperature and the temperature within an enclosurecomprising, in combination, a housing, a portion of the housing beingadapted for insertion into the enclosure; a heat transmitting reservoirsecured to said housing portion so as to extend externally of thehousing effective to partake of the enclosure interior temperature whensaid housing portion is inserted into the enclosure; a wax mixtureincluding at least two waxes having different melting temperatures and asubstance characterized as having substantial thermal conductivitypositioned in the reservoir so as to partake of the enclosure interiortemperature through the reservoir, each wax in the wax mixture beingcharacterized as undergoing substantial volumetric expansion whilemelting; a cover member positioned to prevent the waxes from passingbetween the reservoir and the interior of the housing, the cover memberhaving an aperture which communicates between the interior of thehousing and the interior of the reservoir; an elongated plunger slidablypositioned in the aperture so as to extend into the reservoir and beresponsive to the volume of the wax mixture, volumetric expansion of thewax mixture hydraulically expelling the plunger from the reservoir aseach wax is melted such that the extension of the plunger from thereservoir is indicative of the interior temperature of the enclosure; acontact assembly including a contact support member which contains atleast two apertures and which is driveably coupled to the plunger formovement therewith, first and second electrically isolated contactssupported by the contact support member, and means mechanicallyresponsive to temperature supported by the contact support member foreffecting an electrical connection between the contacts in response tothe ambient temperature; first and second elongated electrical terminalssecured to the housing so as to extend therethrough and be orientedsubstantially parallel with the plunger, the first and second terminalseach being positioned so as to extend through an aperture in the contactsupport member and to be in slidable engagement with one of the contactsand the contact support member such that the first contact is in slidingengagement with the first terminal and the second contact is in slidingengagement with the second terminal, movement of the plunger therebymoving the contacts and the contact support member relative to theterminals, the terminals thereby guiding the contact support member;insulating means positioned within the housing so as to separate thefirst contact from the first terminal when the enclosure interiortemperature has melted the lower melting temperature wax so as topartially expel the plunger from the reservoir, thereby preventing thefirst terminal from being in electrical contact with the second terminalwhen said wax is melted; a third electrical terminal secured to thehousing and extending therethrough so as to be engaged by the secondcontact when both of the waxes are melted by the enclosure interiortemperature and the expulsion of the plunger from the reservoir is at amaximum, the second contact thereby electrically connecting the secondand third terminals when the enclosure interior temperature issufficiently high to melt both of the waxes; and means for biasing theplunger into the reservoir as the waxes are solidified.
 7. A switch thatis responsive to both ambient temperature and the temperature within anenclosure comprising, in combination, a housing, a portion of thehousing being adapted for insertion into the enclosure; a heattransmitting reservoir secured to the housing so as to extend externallyof the housing effective to partake of the enclosure interiortemperature when said housing portion is inserted into the enclosure; amixture of two waxes having different melting temperAtures positioned inthe reservoir so as to partake of the enclosure interior temperaturethrough the reservoir, each wax in the wax mixture being characterizedas undergoing substantial volumetric expansion while melting; a covermember positioned to prevent the waxes from passing between thereservoir and the interior of the housing, the cover member having anaperture which communicates between the interior of the housing and theinterior of the reservoir; a plunger slidably positioned in the apertureso as to extend into the reservoir and be responsive to the volume ofthe wax mixture, volumetric expansion of the wax mixture hydraulicallyexpelling the plunger from the reservoir as each wax is melted such thatthe extension of the plunger from the reservoir is dependent upon theinterior temperature of the enclosure; a contact assembly including acontact support member driveably coupled to the plunger for movementtherewith, first and second electrically isolated contacts supported bythe contact support member, and means mechanically responsive totemperature supported by the contact support member for effecting anelectrical connection between the contacts in response to the ambienttemperature; at least first, second and third electrical terminalssecured to the housing so as to extend therethrough, the first andsecond terminals being positioned so that the first contact is insliding engagement with the first terminal and the second contact is insliding engagement with the second terminal as the plunger moves thecontact assembly, the third terminal being positioned so that the secondcontact is moved into engagement therewith when both of the waxes aremelted by the enclosure interior temperature whereby the second contactelectrically connects the second and third terminals when the enclosureinterior temperature is sufficiently high to melt both of the waxes;insulating means positioned within the housing so as to separate thefirst contact from the first terminal when the enclosure interiortemperature has melted the lower melting temperature wax, therebypreventing the first terminal from being in electrical contact with thesecond terminal when said wax is melted; and means for biasing theplunger into the reservoir as the waxes are solidified.